Small wedding/eloping etiquette help?

Okay so here's the deal, my fiance and I are getting married in a couple of weeks, it's going to be a casual simple wedding ceremony on the beach one state away. We got an inexpensive wedding package. the package can have 20 guests. we're staying with a family friend of mine. We want to elope, and have a big wedding reception when we come back. My fiance wants to invite his mom and gramma to the ceremony. I want them there too, but I want my mom and sister to come too. My mom and sister however say that 2 weeks is too short of notice to come down, and they are low on funds. he says he knows his family would come (they're also not short on funds). I would prefer the wedding to have both sides of the family or just me and him otherwise I think my side of the family would be upset that they couldn't come. Should we try to see if they'll come down or just elope? I don't know how to work this out.I think 2 weeks is too short of notice, he says he doesn't think so. Also, the family we're staying with is good friends of my family, should we invite them to the wedding ceremony? Or would it be rude not to, since we're staying with them? I love them and I would love people to be there, it's just such a short amount of time !